Fibrin foam and process

Abstract

A fibrin wound dressing is made by mixing quantities of fibrinogen solution and thrombin solution with air. The resulting foam is very light weight, and with the proper attention to the amount of thrombin, is also sufficiently viscous to rest on a vertical surface without dripping. The wound dressing may also be formulated for its ability to continue migration of healing substances, such as PDGF, from the dressing to the wound site. Thrombin substitutes, such as other clotting proteins, may be used instead of thrombin. The resulting foam may also be lyophilized or ground and lyophilized for later reconstitution. A therapeutic drug or other additive may also be added to the wound dressing.

What is claimed is: 
     
       1. A method for forming a fibrin foam, the method comprising:
 combining a solution of fibrinogen with air by passing the fibrinogen and air through an inline mixer comprising a three-dimensional lattice defining a plurality of tortuous, interconnecting passages therethrough to form a first foam; 
 combining a solution of a clotting protein with air by passing the clotting protein and air through an inline mixer comprising a three-dimensional lattice defining a plurality of tortuous, interconnecting passages therethrough to form a second foam; and 
 mixing the first and second foams to form a fibrin foam, wherein the fibrin foam has a viscosity sufficient for a thin coating of the fibrin foam to adhere to a vertical surface. 
 
     
     
       2. The method of  claim 1 , wherein the clotting protein is selected from the group consisting of thrombin, a PTC-derived thrombin substitute, and a p-aminoaniline-based protein. 
     
     
       3. The method of  claim 1 , further comprising mixing at least one of the solutions with a therapeutic amount of a calcium-containing compound, an agent, a drug, an antibiotic, or a hormone. 
     
     
       4. The method of  claim 1 , wherein a rate of formation of the fibrin foam is constant in a temperature range from about 15° C. to about 37° C. 
     
     
       5. The method of  claim 1 , further comprising inhibiting the forming of the fibrin foam by adding an effective amount of a photosensitive inhibitor to the solution of clotting protein. 
     
     
       6. The method of  claim 1 , further comprising lyophilizing the fibrin foam to form a lyophilisate, and optionally grinding the fibrin foam or the lyophilisate into a powder. 
     
     
       7. The method of  claim 6 , further comprising reconstituting the fibrin foam by mixing with water or a water solution and optionally adding an additional component. 
     
     
       8. The method of  claim 1 , wherein the mixing step includes mixing the first foam with the second foam by passing the first foam and second foam through an inline mixer comprising a three-dimensional lattice defining a plurality of tortuous, interconnecting passages therethrough to form a fibrin foam.